<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport"
        content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>CSS3 Loading 加载动画</title>
</head>
<style>
  *{
      margin: 0;
      padding: 0;
  }
  body{
      width: 100vw;
      height: 100vh;
      display: flex;
      align-items: center;
      justify-content: center;
  }
  .loading{
      width: 30px;
      height: 30px;
      border-radius: 50%;
      border-width: 5px;
      border-style: solid;
      margin: 25px;
      animation: loading 1s infinite linear;
  }
  .loading-dark,.loading-light,.loading-success,.loading-danger{
      border-bottom-color:transparent;
  }
  .loading .loading-dark{
      border-color: #666666;
  }
  @keyframes loading {
      to{
          transform: rotate(1turn);
      }
  }
</style>
<body>
<div class="loading loading-dark"></div>
<div class="loading loading-light"></div>
<div class="loading loading-success"></div>
<div class="loading loading-danger"></div>
</body>
</html>